Minimising the environmental impact of a process is an important objective
for plant design engineers. It is a goal, however, which is closely linked
to the flowsheet structure and, therefore, must be considered at the concep
tual stage of the design process. At the same time economic criteria are im
portant for the selection of good designs. Frequently, these goals may resu
lt in conflicting designs and compromises are required. In this paper, we d
escribe a multiobjective process synthesis methodology, for the early stage
s of design, suitable for identifying processes with minimal environmental
impact and the desired economic performance. The algorithm is particularly
suitable for synthesising bioprocesses and has been implemented in the Jaca
randa system, which has been enhanced to consider multiple simultaneous cri
teria. The synthesis algorithm is demonstrated and evaluated by applying it
to the synthesis of a penicillin manufacturing process. The procedure is a
ble to identify a set of flowsheets which satisfy both environmental and ec
onomic objectives demonstrating that a multicriteria synthesis tool can be
invaluable for design with multiple objectives. (C) 1999 Elsevier Science L
td. All rights reserved.